The most common lung problem in a premature baby is respiratory distress syndrome (RDS), also known as hyaline membrane disease (HMD). A baby develops HMD when the lungs do not produce sufficient amounts of surfactant, a substance that keeps the tiny air sacs in the lung open. As a result, a premature baby often has difficulty expanding her lungs, taking in oxygen, and getting rid of carbon dioxide. HMD is common in premature babies because the lungs do not usually begin producing surfactant until about the 37th week of pregnancy. Other factors that increase a baby's risk of developing HMD include Caucasian race, male sex, family history, and maternal diabetes. Fortunately, surfactant is now artificially produced and can be given to babies if doctors suspect they are not yet making surfactant on their own. Most of these babies also need extra oxygen and support from a ventilator, either through non-invasive continuous positive airway pressure (CPAP) or an invasive artificial airway, such as an endotracheal tube or tracheostomy tube. Non-invasive ventilation (NIV) is a mechanical ventilation modality that does not utilize an invasive artificial airway (endotracheal tube or tracheostomy tube).
During natural respiration, the air being inhaled is naturally humidified by the nasal cavity and epiglottis. However, when the native nasal passages are bypassed by invasive respiratory therapy, such as with the use of endotracheal tubes, the air must be artificially humidified. Inadequate airway humidification may have serious consequences or cause significant discomfort for patients. For example, one case study showed inspissated secretions, causing life-threatening airway obstruction in a patient using NIV for hypoxemic respiratory failure (Respir Care. 2000 May; 45(5):491-3).
The correct application of a humidification system may avoid the effects of ventilation-induced drying of the airway. Metaplastic changes and keratinization of the nasal epithelium and submucosa have been reported in patients on home NIV when the level of humidification was inadequate for long periods (Thorax. 1995 November; 50(11):1179-82.). These histopathological changes in the nasal mucosa occur relatively early after starting NIV in an acute setting and suggest that humidification should be considered even when only short-term use of NIV is expected.
Conventionally, humidification is done by a passover humidifier which is a system that passes air from the continuous positive air pressure (CPAP) over a room temperature body of water so as to pick up moisture. However, passover humidification only provides sub-optimal humidity.
After that, the humidified air then travels to the patient through tubes. However, when the moistened air cools down moving through the tubes, it condenses and holds less water (a problem known as ‘rainout’). Hence, the conventional tubes in clinical use have a heating wire inside that runs along the length of the tube. Although this temperature control mechanism prevents some condensation, a water plug still forms in the line which interferes with the patient's respiratory therapy. Further, the use of a water reservoir in a passover humidification system raises health concerns, as the water reservoir tends to turn into a breeding ground for bacteria and must be replaced frequently.
Due to the above problems, the conventional respiratory therapy for the neonatal intensive care unit (ICU) exhibits subpar performance. The goal of this invention is to improve the humidity of the conventional passover humidification system, to eliminate condensation and rainout in the tubes and to decrease the amount of bacterial growth in the humidifier reservoir.
All publications herein are incorporated by reference to the same extent as if each individual publication or patent application was specifically and individually indicated to be incorporated by reference. The following description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.